Flow control devices for medical liquid are used for continuously delivering medication, drugs, intravenous solutions and the like to a patient. The flow rate may be adjusted during delivery in order to optimize the flow rate for the current situation, such as a change in a patient's condition.
Conventionally, the flow rate has been adjusted by flow control devices comprising different tubes having different flow restrictions. By selecting through which tube the liquid flows, by means of for example a valve, the flow rate is determined. Or, liquid may flow through several tubes simultaneously for obtaining yet another flow rate to the outlet of the device. Such flow control devices comprise many parts, are relatively big, and are hence complicated and relatively expensive to manufacture. Moreover, these devices conventionally provide only a few flow rates to select from, due to that more available flow rates would require more tubes.
In an attempt to provide a more compact flow control device, the device disclosed in U.S. Pat. No. 6,270,483 comprises a single channel for the liquid flow, which channel can be moved in relation to the inlet part by transferring a rotational movement of a control knob to an axial movement of the channel. The length of the channel from inlet to outlet hence determines the flow rate. Although providing a more compact flow control device than previously known devices, the device is relatively complicated for example requiring a movement conversion mechanism, and it comprises a plurality of parts.
Therefore, there is a need for a flow control device that allows fine regulation of liquid discharge and that is relatively compact and cost-efficient to produce.